how to measure r2dbc response time

[coolxp]

hello. i try use Flux#tap to measure response time, but i find it will run all `save` before run SignalListener#doOnNext.

```

MetricListener<Student> setListener = new MetricListener<>(summary, "set");
Flux.range(1, 10)

    .flatMap(id -> repository.save(new Student(id, "lxp")))

    .tap(() -> setListener)

    .subscribe();

```

why it run this way,and it has some way to measure? thanks

[Mark Paluch]

You might want to have a look at  https://github.com/r2dbc/r2dbc-proxy that allows intercepting R2DBC calls so you can measure how long each interaction lasted.